AS AN INDEX OF AGE. 



61 



Bdfh 



R)sr 



Fig. 1. Diagram of a pollack's scale with three annual rings to show the mode of 

 measurement adopted in the statistical tables. 



Ant = anterior end of scale ; Post = posterior end of scale ; MB" — length of scale ; 

 MB'>"> = maximum breadth of scale ; AB" = long axis from centrum to posterior end of 

 scale ; LB' = total length of 1st year's growth ; AB' = long axis from centrum to posterior 

 end of Ring I ; B^ B^ = long axis from end of Ring I to end of Ring II in posterior direc- 

 tion ; B-B" = long axis from end of Ring II to end of Ring III in posterior direction. 



Enumeration of the lines of growth is taken throughout from the centrum in the 

 posterior direction ; they are more numerous towards the latter than towards the anterior 

 end of the scale. In the tables the signs + and - are used in connection with the occur- 

 rence of annual rings ; for example, if no annual rings are as yet formed the term - 1 is 

 used ; if one annual ring is complete, and there are additional lines of growth present, the 

 sign 1 + is used. 



